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A209953 Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having one, three or four distinct clockwise edge differences. 1
71, 567, 4521, 36057, 287559, 2293335, 18289737, 145863801, 1163288871, 9277428663, 73989087849, 590075690265, 4705955031303, 37530800068887, 299314580024457, 2387085211367865, 19037414768987367, 151826654264588919 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 1 of A209960.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) + 15*a(n-2) + 6*a(n-3).
Empirical g.f.: x*(71 + 141*x + 54*x^2) / (1 - 6*x - 15*x^2 - 6*x^3). - Colin Barker, Jul 14 2018
EXAMPLE
Some solutions for n=4:
..1..1....0..2....0..1....2..1....2..1....2..1....1..2....1..2....1..2....2..1
..0..0....2..1....2..0....0..2....0..2....0..0....0..2....1..1....0..2....2..2
..2..0....0..1....1..2....1..1....2..1....1..1....2..1....1..1....0..2....1..2
..0..0....0..1....2..0....1..2....0..2....1..0....2..0....1..0....2..2....0..2
..0..0....1..1....0..1....1..1....1..0....2..2....0..1....1..2....0..2....2..2
CROSSREFS
Cf. A209960.
Sequence in context: A250982 A250975 A209960 * A251390 A251383 A180327
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 16 2012
STATUS
approved

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)